\documentclass[a4paper]{article}
\usepackage{circuitikz}
\begin{document}
\begin{circuitikz}
  \draw (0,0) to[R, l=$R_1$] (2,0) to[R, l=$R_2$] (4,0) to (6,0);
  \draw (0,-2) to[R, l=$R_3$] (2,-2) to[R, l=$R_4$] (4,-2) to[R, l=$R_x$, v=$V_{pot}$, o-o] (6, -2);
  \draw (2,0) to[V, l=$V_g$, o-o] (2,-2);
  \draw (0,0) -- (0,-2);
  \draw (6,0) -- (6,-2);
  \draw (0,0) to(-1, 0) to (-1, -4) to[V, l=$V_s$] (4, -4) to (6, -4) to (6, -2);

\end{circuitikz}
\end{document}

